Do I need to change the pattern of a purse I make so I can legally sell it?

I am wanting to start making purses and selling them as a side business. I have a few patterns bought from stores and am going to be making my own designs also. I know that on the patterns it says that reproducing and then selling is illegal. I’ve been told if I change the pattern 10% that selling them would be legal. Does anyone know if this is true?

There has to be distinguishable changes and the labels cannot mimic the designer labels in style, color or be closely spelled so as to trick someone into thinking it’s real.

http://crochet.about.com/library/blcopyrightguide.htm?terms=copyright

Vintage Change Purse

Sarut Fic-gp01408 Chicken Coin Purse,1-Pack, Multicolored $13.52 You can never have too many chickens around and this one will carry your loose change, jewelry, lipsticks, school money or odds and ends. Great gift idea….

Blue Q – You’re Beautiful Coin Purse $3.99 Stay just the way you are, but keep that cash well-stowed. Design by Nate Duval. 95% post consumer recycled material. 4.3″w x 3.2″h…

Blue Q – Weed Money Coin Purse $3.99 Meet the naughtly sibling of Lunch Money Coin Purse. Design by 64 Colors. 95% post consumer recycled material. 4.3″w x 3.2″h…

Time for a Change …

Omron HJ-112 Digital Pocket Pedometer $20.00 Omron HJ-112 Pocket Pedometer HJ112 Personal Health Monitors…

Wool Felt Green Apple Daisies Change Wallet (Nepal) $11.49 Carry money, keys and change in style with a handmade felt change purse. Handmade from wool felt by artisans in Nepal, this change wallet features a lovely apple green hue with blue daisies.

Wool Felt Tangerine Daisies Change Wallet (Nepal) $11.49 Carry money, keys and change in style with a handmade felt change purse. Handmade from wool felt by artisans in Nepal, this change wallet features a beautiful color combination of tangerine and yellow.

Soda Pop-top ‘Golden Hope and Change’ Wristlet Bag (Brazil) $62.99 Neide Ambrosio recycles soda pop-tops into a fashion bagGolden color on bag represents hope and changeMetallic bag is crocheted with silken polyester strands and lined with polyester

Foam Change Purse $1.49 Includes (1) assorted Foam Change Purse.

Black Change Purse(Pack of 60) $2.1 Black change purse, with L.A. on sides.

Change Purse With Bills and Coins $24.99 H. Armstrong Roberts Change Purse With Bills and Coins – Photographic Print

Open Purse Filled With Change $24.99 H. Armstrong Roberts Open Purse Filled With Change – Photographic Print